1. Field of the Invention
This invention relates to cassette structures movably supported on the deck of a cargo vessel for holding shipping containers within each cassette and between spaced cassettes.
2. Description of the Prior Art
One problem in designing certain types of ships lies in making them adaptable to various kinds of cargoes, while ensuring an economic operation and an easy handling of the cargo. Much cargo is now made up into units of standardized size, mostly containers, but also flatracks and similar devices. These units may be stowed in cells formed by vertical guides arranged in the cargo holds, as well as upon the weather deck. A desire is to design these guides so they form a strong structure, reducing the inclusion of carrying members in the ships hull.
Many containers and similar cargo units have a length of 20' or 40', while the breadth and height are substantially alike. Conventional "cellguide" systems are often designed for a certain length of container, but attempts have been made to provide flexibility with respect to container length.
British Pat. No. 1 232 306 shows one solution where vertical support and guide members are movable as a unit which can be placed in attachment means at positions corresponding to desired container sizes, other solutions of similar nature are shown e.g. in British No. 1 188 316 and in U.S. Pat. No. 3,552,345.
A drawback with these designs is that guides at one end of a container stack are attached to the ship, separately from the guides at the opposite end of the stack. This necessitates strong members at the points of attachments at the hull.
The shifting of these guides requires considerable lifting facilities, either on board, or at a quay, and every re-disposition to suit a change in size will take up valuable time.